Positive displacement compressor/turbine

ABSTRACT

A positive displacement screw device comprising a pair of housing members in fixed relationship to each other whose adjacent faces are helically threaded but separated to provide passage to and engagement by a plurality of helical rotor blades rotatably supported on a carrier which divide the volume therebetween into expansive pockets, enabling the device to be used as either a fluid pump or motor.

United States Patent 191 Miller, Jr.

[ 1 POSITIVE DISPLACEMENT COMPRESSOR/TURBINE 52nd Avenue, Miami, Flaf33143 [22] Filed: Nov. 5, 1971 21 App1.No.: 195,961

Related US. Application Data [63] Continuation-impart of Ser. No. 59,248, July 29,

1970, abandoned.

[52] US. Cl. ..4l8/55, 418/58, 415/71,

415/72, 74/797 [51] Int. Cl. ..F04c 1/16, F04d 3/02, F03c 3/00 [58] Field of Search ..4l8l55, 58, 220,

[56] Reierences Cited UNITED STATES PATENTS 3/1926 Gilman ..418/55 [451 Apr. 17, 1973 1,738,645 12/1929 Gilman ..4l8/55 2,612,022 9/1952 Keys 2,919,062 12/1959 Tryhom 418/227 Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik Attorney-Julian C. Renfro ABSTRACT A positive displacement screw device comprising a pair of housing members in fixed relationship to each other whose adjacent faces are helically threaded but separated to provide passage to and engagement by a plurality of helical rotor blades rotatably supported on a carrier which divide the volume therebetween into expansive pockets, enabling the device tobe used as either a fluid pump or motor.

27 Claims, 23 Drawing Figures PATENTED APR 1 7 I973 SHEET 2 OF 8 INTAKE w :1 2! Will EXHAUST INVENTOR A A om E, M/LLEE J2.

PATENTEDAPR 1 71975 $728,049

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LLOYD E. LEQJQ.

ATTORNEY PATENTED APR 1 7 I975 SHEET 4 OF 8 L low E. M/m yg ATTORNEY PAIENTEB APR 1 71973 SHEET 5 [1F 8 QNN I.

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ATTORNEY PATENTED 71973 B. 728 O49 SHEET 6 BF 8 EXHAUST INVENTOR Zlova EMA .459 J 2 w mw ATTORNEY PATENTED 1 71973 3.728 O49 sum 7 OF 8 4 1 5? EMT INTAKE INVENTOR Zlova 5 M/LLEP Je.

ATTORNEY PATENTEDAPR171973 3,728 049 SHEET 8 [1F 8 INVENTOR Z1 0Y0 M/LLEA J42 WKW ATH )RNIZY POSITIVE DISPLACEMENT COMPRESSOR/TURBINE RELATIONSHIP TO PRIOR APPLICATION This invention is a Continuation-in-Part of my earlier patent application bearing the same title, filed July 29, 1970, Ser. No. 59,248, which has been allowed, but now abandoned,

This invention relates to a positive displacement compressor/turbine employing a plurality of screw-like helical rotors or blades disposed on a rotatable blade carrier utilized in conjunction with first and second housing members that are configured to form-adjacent helical or spiral threads, between which threads the blades are movable to bring about a volumetric change.

The invention relates in particular to a family of devices which are inherently suitable for the compression or expansion of gases at high flow rates, pressures and temperatures, although these devices may be adapted for handling liquids or slurries with equal benefit.

In the past, a number of rotative devices have been proposed which in principle can be operated either as fluid pumps or as fluid motors, as the case requires, serving to provide a fluid output in response to a mechanical input or alternatively serving to provide a mechanical output as the result of a fluid expansion therethrough. Such devices may be classified into two categories, being How and non-flow types. Generally speaking, flow devices signify machines delivering or receiving a constant flow of fluid such as fans, propellers or turbines which may employ an Archimedes screw or segments thereof. Non-flow devices include the piston and cylinder, vane pumps and to lesser extent gear and Moineau type pumps where the flow is interrupted or pulsed as expansive chambers of finite volume are sequentially exhausted and recharged. Non-flow types usually relate to higher working pressures, but because of low displacement, frictionproducing seals or reciprocating parts, their speed and flow are limited. Conversely, flow types are capable of attaining high flow rates but higher pressures cannot be easily produced, at least in gases, without compounding. Similarly, turbines cannot be throttled or adapted to variable speed applications successfully because of reduced efficiency in the lower speed range.

The present invention overcomes the above objections and disadvantages by the provision of several variations of a positive displacement compressor/turbine which employ first and second helical housing members, each configured with at least one helical thread. The apices of these threads are in continuous alignment with each other to define a spaced pass between the members. A plurality of helical rotor blades having relatively thin minor transverse portions and being rotatable upon their longitudinal axes mesh with the first and second housing members in gear engagement. During operation, minor transverse portions of the rotor blades move through the pass defined between the apices of the first and second member teeth. The rotor blades are in close contact with each other at the pass to define pockets between the first and second members which pockets continuously expand and contract during operation of the device. Port means are provided in the device to permit the ingress and egress of working fluid therethrough.

It is, therefore, a principal object of this invention to provide a device which combines the best features of flow and non-flow machines so that high flow rates and high pressures may be attained or utilized in unison.

A second object of the invention is the provision of a machine having high efficiency in which the rotative elements are used simultaneously as pistons as well as screw propellers to effect a pulseless fluid flow.

Another object of the invention is to provide a device in which no free communication exists between inlet and outlet ports and as a result may be throttled to operate efficiently over a wide speed range.

Still another object of the invention is to provide a device having a bore of maximum size in relation to the outer profile of the machine, and having rotative elements of minimum cross sectional thickness so as to allow unrestricted fluid flow.

An additional object of the invention is the provision of a machine having relatively light weight rotative elements disposed in a symmetrical array so as to offer natural static and dynamic balance without counterweights, to permit high speed vibrationless operation.

Still an additional object of the invention is the provision of a guidance means for insuring precise rotational restraint of the operative elements of the device so as to prevent excessive friction and wear of these parts against non-rotative housing components.

These and other objects, features and advantages of the invention will be more apparent from a study of the appended drawings in which:

FIG. 1 is a perspective view, partly in section, of a principal axial flow embodiment of the invention, utilizing a plurality of helical rotors arranged to orbit in a specially configured housing.

FIG. 2 is a sectionalized side elevation view of the device shown in FIG. 1, but to a somewhat smaller scale, revealing in greater detail some of the interfitting relationships.

FIG. 3 is a cross sectional view taken along lines 3-3 of FIG. 2 showing one of the rotor blades in the pass defined between the single teeth of the housing members.

FIG. 4 is a view similar to FIG. 3, but with the apices of two of the eight rotor blades contacting each other at the pass.

FIG. 5 is an end view of the primary or basic axial embodiment of the invention showing a device with two rotor blades.

FIG. 6 is a sectionalized side elevation view of the device illustrated in FIG. 5, revealing the helical wrap of the fixed central gear member as well as its pitch relationship to the helical rotor blades.

FIG. 7 pertains to a very practical axial embodiment of the invention where three rotor blades may be seen engaged with single-toothed gear housing members.

FIG. 8 is a cross sectional view of an axial embodiment of the invention in which a pair of helical housing members are each configured with two teeth comprising two passes through which the helical rotor blades move.

FIG. 9 is a cross section of an axial device according to the invention in which three-toothed housing members are disposed to form three passes therebetween.

FIG. 10 reveals a guidance means which may be used to provide precise rotational control of the rotor blades employed in the axial embodiments of the invention.

FIG. 1 1 represents a cross sectional view taken along lines 11- l1 in FIG. 10.

FIG. 12 represents a departure from the previous figures in that it pertains to a radial blade, radial flow device in which the near housing member has been removed for clarity.

FIG. 13 is a sectionalized side elevation view of the device shown in FIG. 12 where the blade relationship to both housing members may be seen.

FIG. 14 is a face view of the near housing member which has been removed in FIG. 12, illustrating the single spiral tooth.

FIG. 15 reveals a housing member which can be utilized in a radial blade, radial flow device, in which this member involves two spiral teeth.

FIG. 16 reveals a housing member which can be utilized in a radial blade, radial flow device involving three spiral teeth.

FIG. 17 is a front elevational view of a radial blade, axial flow device in which the housing members each have three spiral aligned teeth.

FIG. 18 is a sectionalized side elevation view of the device shown in FIG. 17, revealing the relationship of the blades to the housing members and to the intake and exhaust ports configured therein.

FIG. 19 is a view like FIG. 17, but with the rotor blades omitted to more clearly show the triangular inlet ports FIG. 20 is an opposite end view from FIG. 17 with blades removed to show the exhaust ports in the second housing member.

FIG. 21 is a sectionalized side elevation view of a blade guidance means that may be employed in conjunction with embodiments of the invention involving radially arrayed rotor blades.

FIG. 22 is a face view taken along lines 22-22 in FIG. 21 of the stator gear employed therein.

FIG. 23 is an end view of one of the blade control gears, taken along lines 23-23 in FIG. 21.

Turning now to FIGS. 1 through 4, an axial flow version 10 of the positive displacement compressor/turbine is there illustrated where a plurality of helical rotor blades orbit between fixed housing members. An annular first housing member 11, also referred to hereinafter as a first gear member 11, is rigidly mounted on a support base as may be observed. A worm-like second housing member 12, also hereinafter referred to as a second gear member or central member 12 is coaxially disposed in a rigid and non-rotative manner within the first gear member 11 so as to create an annular space therebetween, in which space a plurality of rotor blades 13 are disposed to orbit.

A carrier 20 provides means whereby the blades 13 may be orbited and individually rotated while engaging the housing members 11 and 12. As may be seen in FIGS. 1 and 2, the carrier embodies two flanges 21 and 22 which are joined by the hub 23. The carrier is rotatable on its own bearings 24 and 25 which are disposed upon the fixed coaxial shaft 30. Fixed shaft is supported by struts 16 and 17 at one end of the device and indirectly at the other end through drive shaft bearing 29. Shaft 30 also provides support for the non-rotative second housing member 12.

As the name implies, the carrier carries" sets of bearings 26 and 27 which typically receive the journalled shafts 14 of the rotor blades 13. The blades are therefore, individually rotatable about their longitudinal axes and cantilevered or supported from only one end so that their bearings may be isolated from the working fluid of the device.

In the present version, as may be seen in FIGS. 1 through 4, 8 rotor blades 13 are employed, being evenly spaced at 45 degrees upon the carrier 20 is a parallel array. The axis of each blade is disposed at constant radius with respect to the center of rotation of the carrier, being point A in FIG. 3, so that the blades all orbit in the same circle C. Because of this radial symmetry, the entire rotating group is naturally balanced, requiringno extrinsic counterweights for correction.

Each of the housing members 11 and 12, as well as each of the rotor blades 13, is helically configured, which is to say that the interior surface of the first member and exterior surface of the second member are threaded so as to each define a single helical tooth, which teeth or threads wrap through 1% turns with constant helix angle throughout the length of these members. In other words, the members have a 450 degree wrap angle. Since the members each have the same number of threads, in this case being one thread, their helix angles are constant and their lengths are the same, it is obvious that their thread pitch is equal. It is also to be noted that the thread of the first member is positioned with respect to the thread of the second member so as to be in constant alignment throughout their full wrap. This may be expressed differently by saying that both threads start at the same point of angular origin, that the apex of the thread of the first member is disposed exactly adjacent the apex of the thread of the second member, and that this adjacency continues to the termination of the threads at the opposite ends of the members. This provides, therefore, that the root spaces of the threads of the members are also aligned. The threads of both members wrap about the axis of rotation of the carrier 20, point A in FIG. 3.

It is to be further noted that the aligned apices of the first and second members are not touching each other, but are dimensioned to define a pass B or radial space therebetween, as may be seen in FIG. 3, to provide passage to the rotors 13, as will become hereinafter more obvious.

The rotor blades 13, as may be seen, have profiles which resemble twisted ribbons. In essence, the blades are two-toothed helical planetary gears which mesh with the threads of the housing members. Their transverse sections are thin duangles, using the terminology of Franz Reuleaux in The Kinematics of Machinery", page 116, Dover Publications Inc., New York. The sides of the blades which constitute root surfaces are conchoidal, each having the convex curvature of a clam shell. The apices of the teeth of each blade are disposed oppositely at the extremities of the width along the major transverse axis of the duangle. The minor transverse portion of each blade, that is to say the thickness, is deliberately made as thin as structurally possible to provide a minimal flow resistance and which would otherwise, if made thicker, detract from the displacement of the device.

As may be observed, the rotor blades 13 each have a helical wrap angle of five-eighths (5/8) of one turn or 225", which is one-half the wrap angle of the housing members. The blades have a helical thread pitch which is equal to the thread pitch of the housing members. Having this same pitch, therefore, allows the rotor blades to mesh with the helical threads of the housing members in gear engagement. It is required that the housing members and blades have the same direction of helical wrap in order to mesh; which may be either right hand or left hand. The hand employed, of course, determines the direction of fluid flow through the device for a given direction of carrier rotation.

It is significant to note that the apices of the rotor blades are in continuous contact with the housing members except at the pass where the blade apices transfer contact from one housing member to the other. As may be seen in FIG. 4, in the pass zone, the apex of one blade is just touching the apex of an adjacent blade, each having just broken contact with one of the housing members 11 or 12. It should now be obvious that the pass defined between the aligned threads of the housing members is of adequate radial width to provide passage to the minor transverse portions of the rotor blades, as may be seen in FIG. 3. Furthermore, it is the engagement of the root surfaces of each blade with the apices of the housing threads which provides a rotational restraint for each blade. Though it may appear inobvious, each blade is at all times guided during the rotative cycle, inasmuch as a minor transverse portion of each blade is continuously engaging the helically disposed pass defined between the aligned threads of the housing members. In other words, while one cross section through the device might resemble FIG. 4, at least one other cross section would appear as in FIG. 3, so that each blade is provided continuous engagement with a pass at some point along its length to guarantee rotational restraint to each blade. The pass serves further as an abutment against which the pistonlike rotors approach and recede.

It is to be understood that while the carrier 20 positions the blades so that they orbit correctly between the housing members, it is the engagement of the blades with the helical threads of the housing members which prescribes the proper blade rotation. In operation, the blades rotate on their axes one-half turn for each revolution of the carrier. This may be more obvious if it.

is remembered that the rotor blades are two-toothed planetary gears engaging the single-toothed housing gears. Said differently, each time a blade moves through the pass, it has inverted or turned over with respect to the previous transit therethrough. And since the blades have two sides or conchoidal surfaces, each must be carried around in the housing a second time in order to re-invert. With respect to the housing therefore, a blade rotates once for two turns of the carrier, both in the same direction.

The 1:2 ratio as thus described results from the apices of the rotor blades engaging housing members having threads which are'epitrochoidal curves, which may be generated by the well-known method of rolling one Cardan circle geometrically upon another circle. In this instance the first gear member 11 has an interior profile which is a curtate cardioid or heart-shaped figure. Its single tooth relates to the cleft in the heart. The second gear or housing member has an eggshaped cross section where the sharper curvature defines the single tooth disposed thereon. These curves are the loci or traces of the apices of the rotor blades as the blades rotate uniformly on their axes at one-half the speed of the carrier, but in the opposite direction with respect thereto. Engagement of the blades with properly configured housing members as thereby defined, provides that the blades rotate uniformly without cyclic acceleration and deceleration, at onehalf carrier speed, which results in a smooth and vibrationless operation of the device.

The relationship of the blade-to-blade and blade-tohousing members is such, therefore, that the blades divide the annular space between the housing members into expansive pockets whose volumes change continuously as the blades orbit and rotate therebetween; and because the blades have five-eighths turn of helical wrap and the housing members each have 1% turns of wrap, no free communication exists through the device. It follows, that a pressurized fluid applied to either end of the device would cause expansion of the pockets and rotation of the blades. The mechanical reaction of the blades against the housing members would collectively induce a torque in the carrier 20 so that a mechanical output or useful work could be extracted at the carrier drive shaft 28. In addition to the blades acting as pistons, a high velocity flow of fluid through the device would impart a propeller-like rotation to the blades so as to further improve efficiency. In this respect the device could be likened unto a positive displacement turbine. Revers'ibly, the device would be a fluid pump, where mechanical rotation applied to the drive shaft 28 would impart rotation to the carrier and to the blades so as to induce an axial flow of fluid from the inlet end of the device to the exhaust end.

While either end of the device may serve as an inlet depending upon rotation, the axial flow version 10 shown in FIGS. 1 and 2 may be considered as having its inlet at the unsupported ends of the blades, in which a funnel ring 41 and diffuser 42 direct the flow of fluid to the blades.

Although guidance of the blades is inherently provided by their engagement with the housing members, a subsequent embodiment of the invention will provide an extrinsic guidance means to effect a precise rotational control of the blades so as to lessen the frictional contact and wear of the blades. with the housing members, as will be hereinafter described.

Referring to FIG. 5, the most primary form of the invention is there illustrated, wherein a minimum of just two axially disposed rotor blades engage first and second housing or gear members to demonstrate the same principle described in FIGS. 1 through 4. This version distinguishes over the previously described embodiment by employing a relatively smaller second gear member 112 which provides for a greater displacement, though not necessarily smoother flow. As may be seen in the drawing thereof, an annular first member 111 is employed whose interior surface is configured with one helical tooth, and whose transverse profile, as before is a curtate cardioid. A second gear member 1 12 is coaxially disposed within the first member in fixed relationship thereto, and whose cross section is a small egg-shaped one-tooth gear. Support structure for the second member is not shown here but is typical of that employed in the FIG. 1 embodiment. While both members have a helical wrap of two turns or 720, which wrap about point A in FIG. 5, the second member now resembles a coiled spring having a double turn, as may be seen in FIG. 6.

The two helical blades 113 each have a 360 wrap angle (one turn), which is half the wrap angle of the housing members. Both have a duangular cross section as in the previous embodiment, but here utilize a greater blade width. The blades are mounted oppositely on a carrier, which has been omitted along with the blade shafts in FIG. 6 for simplicity, and are individually rotatable in bearings upon the carrier to orbit between the housing members. One blade is shown in FIG. fully engaging the pass defined between the housing members at point B, whose major transverse axis is instantly tangential to the orbit circle C, with apices contacting the cardioid wall of the first housing member. The second blade is shown in proper rotative relationship to the first blade in a radial attitude to the orbit circle, with one of the apices contacting the cardioid wall of the first housing member while its other apex is in contact with the coaxially disposed second housing member 112. Each helical blade 113 sequentially moves through the pass defined between the housing members and at all times the blade apices contact the housing members, except at the pass, so that no free communication exists through the device. It is most significant to note that the rotative relationship of the blades to the housing members is identical to the eight-bladed embodiment of FIG. 1 through 4, except that the wrap angle required to effect closure is greater for the present embodiment.

While the two-bladed construction has a fewer number of working parts, its wider and heavier blades might impose some speed limitation because of centrifugal force, in contrast to an embodiment having more numerous but smaller blades.

In FIG. 7 another version is shown employing singletoothed helical housing members as utilized in the embodiments of FIGS. .1- through 6, but here three axial blades are disposed at 120 degree spacing. This arrangement provides a more substantial central or second gear member in contrast to that used in the twobladed embodiment of FIG. 5. The additional blade provides for less pulsation in the flow of fluid through the device, but the displacement is lower than the twobladed version. In the three-bladed version the housing members require a wrap angle of 1% turns (600) each, while the blades require a wrap angle of five-sixths turn (300) each, to effect closure.

If desired, a greater number of blades could be employed in an embodiment having single-toothed housing members, such as four or more blades, without departing from the spirit of the invention. The amount of wrap angle required to effect closure for the housing members of these single-toothed devices with some given number of blades is equal to 1 [2/(Number of blades)] (turns). The required blade wrap is one-half the amount required for the housing members.

It is interesting to note in these embodiments involving housing members having one tooth, that during rotation the major transverse axes of the blades always point toward the center of the pass on the orbit circle C as is shown by point B in FIG. 7.

Also shown in the drawings are several axially-bladed embodiments of the invention whose housing members each have more than one helical tooth. FIG. 8 shows a unit which employs two teeth, and FIG. 9 employs three teeth. It is to be noted that a device may be constructed according to the invention having four, five or more teeth. When two teeth are used, both housing members are ovals or ellipses but are disposed in cross section with their major axes at right angles so as to define two passes, as may be seen in FIG. 8. Unlike the devices in FIGS. 1 through 7, the rotors always remain parallel to each other as they orbit between the housing members. Such motion may be compared to the seats in a ferris wheel when viewed from the ground. While this embodiment provides nearly a pulseless fluid delivery when employed as a pump, its expansive pockets are considerably smaller resulting in reduced displacement in comparison to the previous embodiments. The device in FIG. 9 is shown only to illustrate the meshing relationship of the rotor blades to the housing members. In this embodiment appreciable axial leakage occurs as the apices of the requisite thicker rotors transfer contact from one housing member to the other at the pass.

In all embodiments of the invention thusfar described, axially disposed blades individually rotatable on a rotatable carrier engage coaxial housing members to comprise a positive displacement device which may serve either as an axial flow fluid pump or fluid motor.

In these devices no constraint is imposed on the blades other than that necessarily involved as the blades engage the helical threads of the housing members during rotation. Reference is now made to FIG. 10 in which an epitrochoidal planetary transmission provides a guidance means whereby friction and wear between the rotor blades and the housing members may be reduced if not eliminated. As may be seen, the device involves planetary control gears 213, which orbit about a fixed sun gear 212. The control gears 213 are in effect extensions of the axial rotor blades which operate in an enclosed carrier 220, provided with a self-contained oil bath. The transmission itself is similar or repetitive in construction to the entire family of axially-bladed devices of the invention, wherein the sun gear 212, which is keyed to the fixed coaxial shaft 230, may be compared with the second housing member 12 in FIGS. 1 through 9. In this instance the outer member has been eliminated and in lieu of, the sun gear 212 isv provided with a helical thread having a double wrap, i.e., two turns, to prevent backlash of the control gears which mesh therewith. As may be observed, the sun gear 212 has but a single thread when employed with the embodiments of the invention involving housings having single teeth, but may have more threads if used with multi-toothed housings. The control gears 213 have duangular transverse sections as illustrated in FIG. 11, and each has a 360 degree wrap angle. The carrier 220 is rotatably disposed on bearings 224 and 225 on the fixed coaxial shaft 230 which extends from the accompanying positive displacement device, not shown. The flanges 221 and 222 of the carrier are held together by the enclosure band 223 which is attached by screws thereto and sealed with o-rings to retain the lubricant contained within the carrier. The control gears each have a shaft extension which couples, as may be seen, with the rotor blades. In operation, therefore, the rotor blades are fully guided by the planetary control gears 2 13 and any torque which is transmitted to or from the drive shaft 228 reacts through the transmission as defined, rather than by means of blade reaction with the housing members. Such guidance thus serves to reduce blade apex wear and leakage and prolongs the life of the rotor blades.

With reference to all axially-bladed embodiments of the invention heretofore described, it is to be noted that no additional compression or expansion, as the case may be, takes place past the point where the rotor blades and housing members have wrapped through sufficient angle to effect positive closure or so that no free communication exists through the device. If more wrap is employed its only function might be to reduce leakage by pluralizing the sealing edges, which is to say, a longer and more devious leakage path would be present through which pressurized fluid might escape.

It is possible, however, to progressively compress or expand the fluid through the device by providing the rotor blades and housing members with helical pitch which is not constant but which varies throughout their length. At any transverse section through such a device, it is to be understood, that the blades and housing members have equal pitch.

Still another method for progressively compressing or expanding the working fluid is to taper the rotor blades and housing members, which again requires that the pitch of the blades and housing members through any transverse section of the device be equal. Such a tapered device would have blade and member axes which would intersect on its smaller end, and because of the obvious similarity to devices in this invention having a parallel array of blades, is omitted in the drawings. It is most important to. note, however, in a tapered device utilizing principles in accordance with the invention, that if the angle of taper were continuously increased, the design limit would be a device in which the blades were disposed in a radial array, and this exactly is the subject of the remaining embodiments of the invention to be hereinafter disclosed.

With reference to FIGS. 12 and 13, there is shown in breakaway views a radial flow embodiment of the invention, in which helically configured rotor blades 313 are disposed in a radial manner on a rotatable mounting member or carrier 320, with the edges or apices of these blades free to engage threaded housing members 311 and 312 positioned on each side of the bladed array. This device is in the general nature of a variable pitch aircraft propeller except that during the rotation of the carrier, which in this case resembles a spinner, the blades rotate continuously on their axes.

As may be observed, the blades are individually rotatable on radially disposed bearings 326 and 327 which are angularly spaced within the carrier relevant to the number of rotor blades employed. With 12 blades, the bearing sets are 30 apart. In addition, the entire carrier assembly with its blades and blade bearings is rotatable on its own main bearings 324 and 325 like a windmill. Each blade has a relatively thin cross section approaching that of sheet metal and has a helical wrap of 180 throughout its length. Also, each blade is of tapered width increasing from the center of the carrier, and when viewed from the end of the device, as in FIG. 12, the blades just touch one another in sealing contact during rotation on their axes. At all times the apices of each blade form at least a single contact with the apex of an adjacent blade. On each side of the bladed array is a coaxially disposed housing member 311, 312 which are stationary and whose faces are contoured with at least one spiral thread so as to engage the rotors while they rotate on their axes during concommitant rotation of the carrier with its array of rotors.

The relationship of the housing members in this embodiment is equivalent to the relationship between the first and second housing members in the previous embodiments, and is such as to form a pass or several passes through which the rotors travel during operation. These passes are formed by positioning the spiral threads on the inner face of each housing member so that they are directly adjacent the spiral thread on the opposite housing member. In other words, the apices of the housing threads are aligned to form a spaced pass which is just of sufficient width to accommodate the thickness or minor transverse portions of the rotor blades while the aligned root spaces permit the passage of the rotor blades as to their width. Since the blades are tapered, so as to contact one another radially, they are also tapered when viewed through a longitudinal section of the device as in FIG. 13.

Because of this taper, the housing faces and associated threads must also be tapered to mesh properly with the rotors. In essence, the housing members are threaded cones, and as may be seen, have equal conical angles. Although it is required that both housing members have the same hand or direction of thread in an as sembled device, when these members are disassembled and laid side by side with theirfaces up, each member has a helical thread which spirals in the opposite direction of the other member, as may be observed by comparing the thread of the housing member in FIG. 12 with that of the removed housing member 311 in FIG. 14. If a single thread is employed on each member, it must have a wrap angle of 360to mate with rotors which have a wrap angle of 180. This provides that each blade is in the pass attitude at some point along its length during rotation.

The total geometric relationship between the blades and the housing members is such here as in the previous embodiments as to form pockets between the blades so that positive closure is afforded and no free communication exists through the device. The inlet to the device would normally be a coaxial port or opening in one or both of the members near the base of the blades around the carrier, and the flow of fluid would be radially outward toward an annular spaced opening between the peripheries of the housing members. The device may be reversibly employed as either a fluid pump or fluid motor. I

It is to be noted from FIGS. 15 and 16 that the housing members may be constructed with more than a single spiral thread if desired and the effect is to create more pass zones and blade rotation.

Referring to FIGS. 17 through 20, may be seen a radially-bladed embodiment of the invention having an axial flow. In this particular instance 12 rotors are employed with their axes disposed in a radial array but with the housing members having three helical threads each. It is to be observed that the inlet and exhaust passages of the former embodiment have been closed off designwise by providing a tubular wall around the periphery of the housing members and connecting therebetween to occlude radial passage of fluid, while the former inlet passage is closed off by allowing the carrier to rotatably and sealingly contact both. housing members.

In the instant embodiment, inlet openings or ports are incorporated in the first housing member while the second or opposite housing member has similar exhaust ports in its face. These ports provide the ingress and egress means for an axial flow of fluid through the device.'The inlet ports, which could also be construed as exhaust ports if the device were rotatably reversed, are disposed l20 apart with their outer contour being the apices of the spiral housing threads, their inner contour the carrier, and the remaining side of each port being a reverse curve similar to a helical blade apex but originating at the carrier near a spiral housing thread and extending irregularly and radially outward and connecting with an adjacent spiral housing thread at its intersection with the periphery of the housing member. The exhaust ports in the opposite housing member are more or less curved triangular aperatures like the inlet ports but are bound'on three sides by the apices of the housing threads, the outer periphery of the housing and have an irregularly curved radial side disposed about one blade-width out of alignment with the counterpart side of a related inlet port. The inlet ports are so con figured as to expose the radially innermost portions of the rotorblades while the exhaust ports expose the outermost portions of the blades.

During rotation of the carrier the blades pass through expansion corridors where the walls of the housing members are not ported. I-Iere, two passes exist at the same rotative point, since one spiral housing thread is ending and another is just beginning. The corridors are actually the aligned root spaces between the members which accommodate the blades as to their width. Through this region fluid is transferred from inlet to exhaust port without any free, communication existing therebetween. In other words, the blades act like fluid metering valves or pistons when traveling through these corridors. Therefore, a pressurized fluid applied .to either set of ports would tend to push the blades through the corridors and thus effect rotation of the carrier and output shaft.

Conversely, if the carrier output shaft were rotated mechanically the blades would act like a pump or cornpressor to induce fluid flow between the inlets and outlets of the device. In addition to acting like a positive displacement device this embodiment, like the other related embodiments of the invention, utilizes also the dynamic flow of fluid across the blades as a propeller to provide an increased efficiency.

It is to be noted that the blades in the present em-' bodiment are fully guided and restrained during rotation by virtue of their contact with the spiral housing threads and do not necessarily require any other extrinsic guiding means such as gears to maintain their proper synchronization. Despite the port openings in the housing walls, the spiral housing threads are not interrupted, which might otherwise interfere with the guidance of the blades. While the inlet ports are here described as being the innermost radially, a design choice for some given application should consider the cenpermits the inlet and exhaust regions of the blades to be 7 more nearly of the same size, considering the aspect of radial taper. Smaller blades are also lighter in weight and pose less of a problem as to centrifugal force, which would otherwise result in higher loads imposed on the blade bearings if fewer and consequently heavier blades were employed. Any number of spiral housing threads may be employed if desired, and it is not required that the device use three threads as hereshown. The number of threads involved, of course, relates directly to the number of ports required and to the extent of blade rotation.

In all of the radially-bladed embodiments, as shown in FIGS. 12 through 20, a blade guidance means may be optionally employed therewith, as was provided the axially-bladed embodiments of the" invention. In FIGS.

'21 through 23 an epitrochoidal spiral bevel gear transmission is illustrated which is related in principle to the planetary transmission shown in FIG. 10, and serves similarly to reduce friction and blade wear in the foregoing radial embodiments. As may be seen in FIG. 21, a carrier 520 is rotatably disposed upon its drive shaft 528 which is journalled in bearings 524 and 525. A plurality of radially disposed blade control gears 513 are individually rotatable in bearings 526 and 527 upon the carrier and positioned to engage the non-rotative spiral bevel gear 511 which is supported on the fixed shaft 530. The control gears 513 have extended shaft portions which are pinned or otherwise coupled to the radial blades 313, 413, of the pertinent displacement device, the latter being omitted for simplicity in FIG. 21 except for portions of the blades.

Each blade control gear 513 is tapered, having a conical envelope, duangular cross section, as in FIG. 23, and a helical thread wrap of 360 degrees. The fixed or stator bevel gear 511 has at least a single thread, which is epitrochoidal with a spiralwrap of two turns, as may be seen in FIG. 22. The number of threads employed on the stator gear is, of course, equal to the number of threads on either housing member of the displacement device with which this transmission is employed.

During rotation of the carrier, the control gears mesh with the stator bevel gear, to provide, as should now be obvious, a precise rotational control of the rotor blades, without the blades being dependent upon engagement with the walls of the associated displacement device for synchronization.

It is to be noted that a transmission device may be constructed, if desired, in which the control gears are disposed in a conical array for use in a displacement device having a similarly tapered array of rotor blades, without departing from the spirit of the invention.

Likewise, it is within the scope of the invention that any of the devices as herein defined, may be constructed as kinematic inversions, in which case for example, the housing members might be rotatively disposed, the carrier eliminated and the blades disposed individually rotatable from a fixed support.

Having thus described my invention, I claim:

1. A positive displacement device comprising first and second gear members disposed in fixed relationship to each other, being configured to define at least one helical thread on each said member, a plurality of helical blade gears individually rotatable which operate between said first and second gear members, said blade gears engaging said helical threads of said first and second gear members to define moving pockets during rotation of said blades.

2. The device as defined in claim 1 in which said helical blade gears are disposed in essentially a parallel array, said first gear member being a generallyannular housing and internally threaded, said second gear member disposed therein and being worm-like and externally threaded.

3. The device as defined in claim 2 including an epitrochoidal helical planetary gear transmission connected thereto comprising a sun gear member having at least one external epitrochoidal helical tooth thereon, and at least one helical planetary gear having at least two external teeth rotatively disposed to mesh therewith.

4. The device as defined in claim 3 in which a plurality of said helical planetary gears are employed as extensions of the essentially parallel blades as a guidance means to provide precise rotational blade control. I

5. The device as defined in claim 1 in which said helical blade gears are disposed in essentially a radial array, said first and second gear members being housing members having inner faces configured as threaded cones.

6. The device as defined in claim 5 including an epitrochoidal spiral bevel gear transmission connected thereto comprising a bevel gear member configured to define at least one epitrochoidal helical tooth thereon, and a helical bevel gear rotatively disposed to mesh therewith.

7. The device as defined in claim 6 in which a plurality of said helical bevel gears are employed as extensions of the radial blades as a guidance means to provide precise rotational blade control.

8. The device as defined in claim 1 in which said helical blade gears are disposed individually rotatable upon a rotatable blade carrier.

9. The device as defined in claim 8 in which the device serves as a fluid motor so as to provide a shaft output at said blade carrier in response to a pressurized fluid input.

10. The device as defined in claim 8 in which said device serves as a pump so as to provide a flow of fluid in response to a mechanical input to said blade carrier.

11. A device of the class described comprising coaxial first and second housing members, said members being each configured to define thereon at least one helical tooth, apices on said teeth of said members, said apices of said first member being in continuous alignment with said apices of said second member and spaced to define at least one pass therebetween, a plurality of helical rotor blades having relatively thin mirror transverse portions, said blades each having a longitudinal axis and being rotationally disposed thereupon, said blades meshing with said helical teeth of said first and second members in gear engagement, said minor transverse portions of said rotor blades moving relatively through said pass defined between the apices of said first and second member teeth during operation,

said rotor blades being in close contact with each other at said pass to define pockets between said first and second members, said pockets continuously moving during operation of the device, and port means for providing the ingress and egress of fluid through the device.

12. The device as defined in claim 11 in which each of said helical rotor blades has two helical teeth, and whose transverse section defines a thin duangle having conchoidal sides. 1

13. The device as defined in claim 11 in which each of said blades has constant width and whose apices are parallel. Y

14. The device as defined in claim 11 in which each of said blades has tapered width and whose apices are not parallel.

15. The device as defined in claim 11 in which the loci of the apices of said rotor blades are epitrochoidal curves, which curves define the operable surfaces of said first and second housing members.

16. The device as defined in claim 11 in which said first member has a transverse section whose interior curvature is a curtate cardioid and in which said second member has a transverse section whose exterior curvature is generally egg-shaped, said curvatures comprising one-toothed gears whose apices are aligned to define a pass therebetween.

17. The device as defined in claim 11 in which said first member and said second member have interior and exterior surfaces, respectively, whose transverse sections are ellipses, said ellipses being two-toothed gears whose apices are aligned to define passes therebetween.

18. The device as defined in claim 11 in which said first member and said second member have interior surfaces and exterior surfaces, respectively, whose transverse sections are triangular, being three-toothed gears whose apices are aligned to define passes therebetween.

19. The device as defined in claim 11 in which said first and second members are operable surfaces which are conical, being each configured with at least one spiral epitrochoidal thread whose apices are aligned to define a pass therebetween.

20. The device as defined in claim 11 in which the helical pitch of said first and second members and said blade gears is equal and constant.

21. The device as defined in claim 11 in which the helical pitch of the said first and second members and said blade gears is equal through any transverse section of the device.

22. An axially-bladed device as defined in claim 11 in which said port means are disposed oppositely between the ends of said first and second gear members to provide an axial flow of fluid therethrough.

23. A radially-bladed device as defined in claim 11 in which said port means comprise essentially curved triangular apertures through said first and second housing members, said apertures being related in number to the number of helical threads of said members and disposed to provide an axial flow of fluid therethrough.

24. The device as defined in claim 11 in which said first and second members and said helical blade gears have sufficient helical wrap so that no free communication exists through the device.

25. The device as defined in claim 11 in which said first and second members and said helical blade gears have the same hand of helical wrap.

26. A radially-bladed device as defined in claim 11 in least one of said housing members and an annular peripheral port between said first and second members which said port means comprise a coaxial port in at 

1. A positive displacement device comprising first and second gear members disposed in fixed relationship to each other, being configured to define at least one helical thread on each said member, a plurality of helical blade gears individually rotatable which operate between said first and second gear members, said blade gears engaging said helical threads of said first and second gear members to define moving pockets during rotation of said blades.
 2. The device as defined in claim 1 in which said helical blade gears are disposed in essentially a parallel array, said first gear member being a generally annular housing and internally threaded, said second gear member disposed therein and being worm-like and externally threaded.
 3. The device as defined in claim 2 including an epitrochoidal helical planetary gear transmission connected thereto comprising a sun gear member having at least one external epitrochoidal helical tooth thereon, and at least one helical planetary gear having at least two external teeth rotatively disposed to mesh therewith.
 4. The device as defined in claim 3 in which a plurality of said helical planetary gears are employed as extensions of the essentially parallel blades as a guidance means to provide precise rotational blade control.
 5. The device as defined in claim 1 in which said helical blade gears are disposed in essentially a radial array, said first and second gear members being housing members having inner faces configured as threaded cones.
 6. The device as defined in claim 5 including an epitrochoidal spiral bevel gear transmission connected thereto comprising a bevel gear member configured to define at least one epitrochoidal helical tooth thereon, and a helical bevel gear rotatively disposed to mesh therewith.
 7. The device as defined in claim 6 in which a plurality of said helical bevel gears are employed as extensions of the radial blades as a guidance means to provide precise rotational blade control.
 8. The device as defined in claim 1 in which said helical blade gears are disposed individually rotatable upon a rotatable blade carrier.
 9. The device as defined in claim 8 in which the device serves as a fluid motor so as to provide a shaft output at said blade carrier in response to a pressurized fluid input.
 10. The device as defined in claim 8 in which said device serVes as a pump so as to provide a flow of fluid in response to a mechanical input to said blade carrier.
 11. A device of the class described comprising coaxial first and second housing members, said members being each configured to define thereon at least one helical tooth, apices on said teeth of said members, said apices of said first member being in continuous alignment with said apices of said second member and spaced to define at least one pass therebetween, a plurality of helical rotor blades having relatively thin mirror transverse portions, said blades each having a longitudinal axis and being rotationally disposed thereupon, said blades meshing with said helical teeth of said first and second members in gear engagement, said minor transverse portions of said rotor blades moving relatively through said pass defined between the apices of said first and second member teeth during operation, said rotor blades being in close contact with each other at said pass to define pockets between said first and second members, said pockets continuously moving during operation of the device, and port means for providing the ingress and egress of fluid through the device.
 12. The device as defined in claim 11 in which each of said helical rotor blades has two helical teeth, and whose transverse section defines a thin duangle having conchoidal sides.
 13. The device as defined in claim 11 in which each of said blades has constant width and whose apices are parallel.
 14. The device as defined in claim 11 in which each of said blades has tapered width and whose apices are not parallel.
 15. The device as defined in claim 11 in which the loci of the apices of said rotor blades are epitrochoidal curves, which curves define the operable surfaces of said first and second housing members.
 16. The device as defined in claim 11 in which said first member has a transverse section whose interior curvature is a curtate cardioid and in which said second member has a transverse section whose exterior curvature is generally egg-shaped, said curvatures comprising one-toothed gears whose apices are aligned to define a pass therebetween.
 17. The device as defined in claim 11 in which said first member and said second member have interior and exterior surfaces, respectively, whose transverse sections are ellipses, said ellipses being two-toothed gears whose apices are aligned to define passes therebetween.
 18. The device as defined in claim 11 in which said first member and said second member have interior surfaces and exterior surfaces, respectively, whose transverse sections are triangular, being three-toothed gears whose apices are aligned to define passes therebetween.
 19. The device as defined in claim 11 in which said first and second members are operable surfaces which are conical, being each configured with at least one spiral epitrochoidal thread whose apices are aligned to define a pass therebetween.
 20. The device as defined in claim 11 in which the helical pitch of said first and second members and said blade gears is equal and constant.
 21. The device as defined in claim 11 in which the helical pitch of the said first and second members and said blade gears is equal through any transverse section of the device.
 22. An axially-bladed device as defined in claim 11 in which said port means are disposed oppositely between the ends of said first and second gear members to provide an axial flow of fluid therethrough.
 23. A radially-bladed device as defined in claim 11 in which said port means comprise essentially curved triangular apertures through said first and second housing members, said apertures being related in number to the number of helical threads of said members and disposed to provide an axial flow of fluid therethrough.
 24. The device as defined in claim 11 in which said first and second members and said helical blade gears have sufficient helical wrap so that no free communication exists through the device.
 25. The device as defined in claiM 11 in which said first and second members and said helical blade gears have the same hand of helical wrap.
 26. A radially-bladed device as defined in claim 11 in which said port means comprise a coaxial port in at least one of said housing members and an annular peripheral port between said first and second members to provide a radial flow of fluid there-through.
 27. The radially-bladed device as defined in claim 26 in which the annular peripheral port between said first and second housing members is closed by a tubular partition. 